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Post by dubiousgolfer on Oct 27, 2019 8:50:51 GMT -5
Hi DG, It's not from parallax. From a face-on view, the degree of curvature for release can be reasonably assessed, about which Dr. Mann made a reasonable comment. I was pointing out why Toms' downswing was more of a "U" than a "V." S Hi S I made a you-tube video just now to explain Parallax error . Unless there was a big change in the hub path plane angle (compared to horizontal ), the parallax error effect would probably be quite small (so not really a viable explanation to explain the extent of curvilinear path that triggers release in JS, DJ, Champ hub path). DG
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Post by imperfectgolfer on Oct 27, 2019 9:06:28 GMT -5
Dr. Mann, David Toms, with a lengthy 90 degree right arm bend, comes into delivery with a "high pointing" right forearm. The others you used for comparison have more forward bend and thus don't have the high pointing forearm. Toms procedure is why, from a face-on view, the hand path appears circular and not nearly as vertical as the others. I think that the Athletic Motion production is a fair assessment for the comparative iron swings except that, to get a more complete picture, the timing of left arm adduction to abduction should be covered with the extent of chest rotation. The two work in tandem. Driving swings can generally be analyzed in the same context except that the ball is effectively more forward in the stance and angle of attack is shallower. Champ is an interesting one to view as the trajectory of his stock drive is very low from a forward leaning shaft. It would be interesting to see how he changes his swing to hit a higher trajectory shot. S You state that DT has a "high-pointing" right forearm. I presume that you mean that it is more horizontal compared to the right forearm angle of DJ and CC, where their right forearm is angled more groundwards. That "fact" is simply due to the fact that DT does not get his hands below waist level at P5.5 while DJ and CC get their hands significantly lower (below waist level) by P5.5. Jeff.
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Post by dubiousgolfer on Oct 27, 2019 9:27:58 GMT -5
I have no doubt that the clubshaft is under tension before P5.5 (at the start of the release of PA#2), but that phenomenon does not exist in the later downswing after the release of PA#2 (which causes the peripheral clubshaft to be bent forward relative to the proximal clubshaft). Jeff. Dr Mann I am finding the physics very frustrating to explain the golf swing . Do you think anyone really knows for certain? This is what I intuitively know: 1. I'm applying forces on the golf grip 2. The only way I can move the COM (ie.clubhead) of the golf club is via : a. The tension forces along the shaft b. Distorting the club handle (by bending and twisting) so that the rest of the shaft ,closer to the clubhead, tries to recover its shape. As you infer , there must be some tension in the shaft before 'Release' (ie. before P5.5) and that must be accelerating the clubhead (point 2a above) plus I am also creating lagging bend in the shaft (point 2b above) and the 'restoring forces ' of the the shafts medium might accelerate the club by a small amount. But when the forward bend happens , the golfer cannot be using the 'bending' aspect of point 2b above to accelerate the clubhead . So by a matter of elimination it must be point 2a that is providing any increase in clubhead speed from P5.5 to P7 (what else could it be?). The tension in the clubshaft must have been large between the beginning of PA#2 'release' (ie. 5.5) to maybe P6.5 to create such clubhead speed. All I know is that a physical force must be moving the clubhead and that can only be achieved via forces through the medium (ie. the shaft material) that is attached to it. DG
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Post by imperfectgolfer on Oct 27, 2019 11:45:17 GMT -5
DG, You wrote-: " This is what I intuitively know:
1. I'm applying forces on the golf grip 2. The only way I can move the COM (ie.clubhead) of the golf club is via : a. The tension forces along the shaft
b. Distorting the club handle (by bending and twisting) so that the rest of the shaft ,closer to the clubhead, tries to recover its shape."
Regarding the release of PA#2, I think that it is a major mistake to think that a golfer can only release the club by doing "something" with respect to tension forces in the clubshaft (which I think is a minor element of little relevance). I think that one should think of forces causing the uncocking of the left wrist and I think that the D'Alembert principle provides a reasonably satisfactory explanation that explains why the left wrist uncocks during the release of PA#2 - based on the effect of changes in hand arc directional travel on the COM of the clubshaft that causes it to gain angular momentum when the hand arc changes its direction from being "straightish" to more "tightly" circular. The peripheral clubshaft bending forward after P6.2 is simply a side-effect of the "fact" that the COM of the clubshaft abruptly acquires a lot of angular momentum between P5.5 and P6.2 due to the D'Alembert principle causing the release of PA#2.
Jeff.
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